TWI441574B - Metal base circuit substrate - Google Patents

Description

Metal base circuit substrate

The present invention relates to a metal base circuit substrate used in a field requiring heat dissipation and thinning of a liquid crystal display device or the like. The liquid crystal display device uses an LED (Light-emitting diode) as a light source.

Examples of the light source of the liquid crystal backlight include a CCFL (Cold Cathode Fluorescent Lamp) or an LED.

CCFL has the advantages of easy use and long life. LED has excellent color reproducibility, high brightness and thin shape. Because it does not use mercury, it has low environmental load, vibration resistance and impact resistance compared with CCFL. It is used in the temperature range of the range (-40°C~85°C), and has the advantage of 50,000 hours of life depending on the environment.

The luminous efficiency of the LED is lower than that of the CCFL. Therefore, in a sealed space similar to the inside of the liquid crystal backlight, the temperature in the vicinity of the LED tends to be higher than that of the CCFL. Under such conditions, since the brightness is lowered and the current value needs to be increased, the heat generation is increased and the temperature is increased.

Therefore, as the temperature of the LED rises, the deterioration of the semiconductor element is promoted, resulting in a shortened life of the LED. Therefore, heat dissipation is required on a printed circuit board on which an LED is mounted.

As a method of dissipating heat of a printed circuit board on which an LED is mounted, there is a method of transmitting heat to a frame by transmitting a thermally conductive material on a printed circuit board (see Patent Document 1). However, this method is difficult to dissipate heat to the frame on a single printed circuit board, and a sub-member is required, which causes an increase in cost, which is not preferable.

In another heat-dissipating method, there is a structure in which a heat-dissipating portion having a circuit pattern of a printed circuit board is passed through a heat-dissipating hole to allow heat to escape from the frame body (see Patent Document 2). However, there is a problem that the composition of the substrate is complicated.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-353388

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2007-12856

In the present invention, in the substrate for LED backlight, it is possible to have good heat dissipation characteristics and suppress the amount of bending without using sub-members or heat dissipation holes, thereby improving circuit formation and LED mounting of a printed circuit board. Workability at the time.

That is, according to the present invention, there is provided a metal base circuit substrate comprising: an insulating layer having a coefficient of linear expansion of 60 ppm/° C. or more and 120 ppm/° C. or less; a metal foil formed of a metal material and provided in the insulating layer One side of the layer, the coefficient of linear expansion is 10ppm/°C or more, 35ppm/°C or less; the circuit part and the non-circuit part are formed on the other side of the insulating layer, and the coefficient of linear expansion is 10ppm/°C or more and 35ppm/°C or less; a film formed on the insulating layer, the circuit portion, and the non-circuit portion, the total area of the circuit portion and the non-circuit portion on the insulating layer being 50% or more and 95% or less with respect to the area of the metal foil, and the line of each material The relationship of the expansion coefficient is: the linear expansion coefficient of the insulating layer > the linear expansion coefficient of the metal foil > the linear expansion coefficient of the circuit portion and the non-circuit portion.

In addition, in one aspect of the invention, a metal base circuit substrate is provided, wherein the insulating layer is formed of an epoxy resin, a hardener, and an inorganic filler, and the inorganic filler contains 40% by volume with respect to the total volume of the insulating layer. Above 70% by volume.

Further, in one aspect of the invention, there is provided a metal base circuit substrate, wherein the curing agent contains a substance having one or both of a hydroxyl group and an amine group.

Further, in one aspect of the invention, there is provided a metal base circuit substrate, wherein the white film contains titanium dioxide as a white pigment, a titanium dioxide-based rutile type, and a surface coated with aluminum hydroxide or cerium oxide.

According to the present invention, in the substrate for LED backlight, since the sub-member or the heat dissipation hole is not used, the heat dissipation property can be improved, so that the life of the LED can be prolonged and the amount of bending can be suppressed, whereby the printed circuit board can be improved. The workability at the time of circuit formation and LED mounting.

Hereinafter, a metal base circuit substrate according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a schematic view showing a hybrid integrated circuit module using a metal base circuit board according to an embodiment of the present invention, and is a cross-sectional view showing a metal base circuit board.

As shown in Fig. 1, the metal base circuit board of the present embodiment includes a metal foil 1, an insulating layer 2, a circuit portion 3 formed on the surface of the insulating layer 2 on which the metal foil 1 is not provided, and an insulating layer. The non-circuit portion 4 on the surface of the layer 2 on which the metal foil 1 is not provided; and the white film 5 formed on the insulating layer 2 and the circuit portion 3 and the non-circuit portion 4.

As shown in FIG. 1, the LED package 7 is mounted on the circuit portion 3 through the soldering portion 6, thereby forming a hybrid integrated circuit module.

The metal base circuit board of the present embodiment is characterized in that the insulating layer has a linear expansion coefficient of 60 ppm/° C. or more and 120 ppm/° C. or less; the metal foil is formed of a metal material and is provided on one side of the insulating layer. The coefficient of linear expansion is 10 ppm/° C. or more and 35 ppm/° C. or less; the circuit portion and the non-circuit portion are formed on the other side of the insulating layer, and the coefficient of linear expansion is 10 ppm/° C. or more and 35 ppm/° C. or less; and a white film is formed. On the insulating layer, the circuit part and the non-circuit part.

Further, the total area of the circuit portion and the non-circuit portion on the insulating layer is 50% or more and 95% or less with respect to the area of the metal foil. Moreover, the relationship between the linear expansion coefficients of the materials is: the linear expansion coefficient of the insulating layer > the linear expansion coefficient of the metal foil > the linear expansion coefficient of the circuit portion and the non-circuit portion.

[circuit part and non-circuit part]

In the present invention, the circuit portion and the non-circuit portion are formed of the same conductive material (conductor metal) provided on the insulating layer, and the circuit portion means to drive the electron. A circuit portion in which a current flows with an electrical component. Further, in the present invention, the non-circuit portion means a conductive material (conductor metal) which is disadvantageous for electrical use.

In the metal base circuit board of the present embodiment, the total area of the non-circuit portion 4 and the circuit portion 3 on the insulating layer 2 is 50% or more and 95% or less.

When the total area is 50% or more, the bending of the metal base circuit board can be suppressed, and the mounting of the electronic component mainly including the LED can be easily performed. Further, when the total area is 95% or less, the space between the circuit portion and the non-circuit portion can be sufficiently ensured, and electrical reliability can be ensured.

In the metal base circuit board of the present embodiment, the linear expansion coefficient of the circuit portion 3 and the non-circuit portion 4 is 10 ppm/° C. or more and 35 ppm/° C. or less.

As the conductor material of the circuit portion 3 and the non-circuit portion 4, a conductor material having the above-described linear expansion coefficient can be suitably selected, and specifically, Ni, Cu, Al, Fe, Si, a stainless steel monomer, and the like are available.

Among them, Cu, Al or an alloy of Cu and Al is preferable in view of heat dissipation.

In the metal base circuit board of the present embodiment, the thickness of the circuit portion 3 and the non-circuit portion 4 is preferably 18 μm or more and 70 μm or less.

When the thickness of the circuit portion 3 and the non-circuit portion 4 is 18 μm or less, there is a problem that wrinkles and the like are likely to occur due to manual operation when manufacturing the metal base circuit substrate. Further, when the thickness of the circuit portion 3 and the non-circuit portion 4 is 70 μm, problems occur in the patterning of the circuit portion and the non-circuit portion.

[metal foil]

In the metal base circuit board of the present embodiment, the linear expansion coefficient of the metal material constituting the metal foil 1 is 10 ppm/° C. or more and 35 ppm/° C. or less.

As the metal of the metal foil, a metal having the above linear expansion coefficient can be suitably selected, and specifically, Ni, Cu, Al, Si, Fe, a stainless steel monomer, and the like are available.

Among them, Cu, Al or an alloy of Cu and Al is preferable in view of heat dissipation.

In the metal base circuit board of the present embodiment, the thickness of the metal foil 1 is preferably 150 μm or more and 300 μm or less.

When the thickness of the metal foil 1 is 150 μm or more, it is possible to suppress the problem of being bent by manual operation when manufacturing the metal base circuit board, and it is preferable that the thickness of the liquid crystal display device is 300 μm or less.

[Insulation]

In the metal base circuit board of the present embodiment, the linear expansion coefficient of the insulating layer 2 is 60 ppm/° C. or more and 120 ppm/° C. or less.

As the material of the insulating layer, an insulating material having the above linear expansion coefficient can be suitably selected, and specific examples thereof include an epoxy resin, an anthrone resin, and the like.

Among these, from the viewpoint of heat resistance and adhesion to metal, an epoxy resin is particularly preferable.

The resin may suitably contain a curing agent or an inorganic filler, and may further contain an additive to improve the wettability or grade of the substrate and to promote the decrease in viscosity, thereby reducing the occurrence of defects during formation.

As such an additive, for example, a foam remover, a surface conditioner, a wetting dispersant, and the like are available.

In the metal base circuit board of the present embodiment, the thickness of the insulating layer 2 is preferably 80 μm or more and 180 μm or less.

When the thickness of the insulating layer 2 is 80 μm or more, the insulating property can be easily ensured, and when it is 180 μm or less, the insulating layer can be easily and uniformly formed.

As the epoxy resin used for the insulating layer 2, a known epoxy resin can be used, and examples thereof include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, and resorcinol. Diglycidyl ether, hexahydro-bisphenol A diglycidyl ether, polypropylene glycol ether, neopentyl glycol diglycidyl ether, diglycidyl phthalate, dimerized acid diglycidyl ester, triglycidyl Isocyanate, tetraglycidyldiaminediphenylmethane, tetraglycidyldiamine-m-xylene, phenolic polyglycidyl ether, tetrabromobisphenol A diglycidyl ether, bisphenol hexafluoroacetoxyglycidyl An epoxy group-containing substance such as ether.

Among these, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether are preferable in view of heat resistance and adhesion to metal.

The chloride ion concentration in the epoxy resin is preferably 1000 ppm or less, more preferably 500 ppm or less.

When the concentration of the chloride ion in the epoxy resin composition is high, the ionic impurities are caused to move under high temperature, high humidity, direct current, or even an alternating voltage, and electrical insulating properties tend to be lowered.

As the curing agent for the epoxy resin, a substance having one or both of a hydroxyl group or an amine group which reacts with an epoxy group is preferred. For example, it has a polyamine or a polyphenol which is a hardener of this epoxy resin.

In the case of using a hardener of an epoxy resin, particularly a substance containing a hydroxyl group, a hardening accelerator may also be used.

As the hardening accelerator, imidazoles are preferred. For example, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-dimethylimidazole, 2-methyl-4-methylimidazole, 2-phenylimidazole, 2- Phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a Benzimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2,4-diamino-6-{2'-methylimidazolium-(1')}-ethyl-s-three 2,4-Diamino-6-{2'-undecylimidazole-(1')}-ethyl-s-three Preferably, 1-cyanomethyl-2-methylimidazole or the like is preferred.

Among these, from the viewpoint of improving moisture resistance reliability and Tg (glass transition temperature), 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole is particularly preferable.

The amount of the hardening accelerator added is preferably 0.005 parts or more and 5 parts or less.

When the addition amount of the hardening accelerator is 5 parts or less, the operation time is increased, and the workability due to the increase in viscosity can be suppressed. When the amount is 0.005 parts or more, the high-temperature heating time at the time of curing becomes short, and the cost is reduced. It is ideal from the viewpoint of workability.

The inorganic filler contained in the insulating layer 2 is preferably electrically insulating and excellent in thermal conductivity, and has, for example, cerium oxide, aluminum oxide, aluminum nitride, tantalum nitride, boron nitride, or boron nitride. Magnesium oxide. Among them, in particular, cerium oxide, aluminum oxide, and aluminum nitride are preferable from the viewpoint of electrical insulating properties and thermal conductivity.

The sodium ion concentration in the inorganic filler is preferably 500 ppm or less, more preferably 100 ppm or less.

When the sodium ion concentration in the inorganic filler is 500 ppm or less, the movement of the ionic impurities is less likely to occur under high temperature, high humidity, direct current or even alternating voltage, and the decrease in electrical insulation properties can be suppressed.

The content of the inorganic filler contained in the insulating layer 2 is preferably 40% by volume or more and 70% by volume or less based on the total volume of the insulating layer.

When the content of the inorganic filler is 40% by volume or more, sufficient thermal conductivity can be obtained, and when it is 70% by volume or less, when the insulating layer 2 is formed, defects are not easily generated, and the withstand voltage is not impaired. Adhesion.

Further, in order to avoid an increase in viscosity due to the inorganic filler, it is preferred to mix two or more kinds of inorganic fillers having different particle diameters.

The thermal conductivity of the insulating layer 2 after hardening is 1W/m. K or more is preferred, especially 2W/m. K or more is better.

When hardened, the thermal conductivity is 1W/m. When K or more, the heat generated from the electronic component can be efficiently dissipated to the back side of the metal base circuit substrate, and by externally dissipating heat, the heat storage of the electronic component can be reduced, and the temperature rise of the electronic component can be reduced. A long-life hybrid integrated circuit module is available.

In addition, in order to ensure insulation when a voltage is applied to the circuit portion after mounting an electronic component such as an LED, the breakdown voltage of the insulating layer 2 is preferably 1.8 KV or more, and more preferably 2 kV or more.

In the metal base circuit board of the present embodiment, the relationship between the linear expansion coefficient of the metal material constituting the metal foil, the linear expansion coefficient of the insulating layer, and the linear expansion coefficient of the circuit portion and the non-circuit portion is preferably the following relationship: The linear expansion coefficient of the layer > the linear expansion coefficient of the metal foil > the linear expansion coefficient of the circuit portion and the non-circuit portion.

It is preferable that the linear expansion coefficient of the metal material constituting the metal foil is larger than the linear expansion coefficient of the circuit portion and the non-circuit portion, in order to reduce the linear expansion coefficient of the circuit portion which does not want to be bent, so as to suppress the insulation layer. The bending at the time of forming the circuit portion and the non-circuit portion satisfactorily maintains the workability in circuit formation and LED mounting.

The non-circuit portion 4 of the insulating layer 2 and the surface on the side on which the circuit portion 3 is placed are preferably smooth and have good light reflectivity. In particular, in order to increase the adhesion, the adhesion surface between the non-circuit portion 4 and the circuit portion 3 on the insulating layer 2 is preferably subjected to surface roughening treatment, plating, decane coupling treatment, or the like.

In order to ensure connection reliability after mounting electronic components such as LEDs, the 90°C peel strength of the insulating layer 2 and the [circuit portion 3 and the non-circuit portion 4] is preferably 1 kg/cm or more, and is 1.4 kg/cm. The above is better.

[white film]

The resin used as the white film 5 is preferably one or more types of thermosetting resin or photocurable resin. The thermosetting resin may be an epoxy resin, and the photocurable resin may be an acrylic resin.

As the resin used as the white film 5, a white pigment containing one or more kinds of titanium dioxide, barium sulfate, talc, cerium oxide or the like is preferable as the white pigment.

In particular, those containing titanium dioxide are preferred because of their large refractive index and high reflectance of light of the substrate.

Further, since the titanium dioxide-based rutile type has excellent stability, the photocatalytic action is weak, and deterioration of the resin component can be suppressed as compared with other structures, which is preferable. Further, in order to suppress the photocatalytic action, it is preferred that the surface thereof be coated with aluminum hydroxide or cerium oxide.

The content of the white pigment is preferably 30% by mass or more and 75% by mass or less based on the composition of the white film 5.

When the content of the white pigment is 30% by mass or more, sufficient reflectance can be obtained, and when it is 75% by mass or less, the grade is not lowered due to an increase in viscosity, a smooth coating film can be obtained, and reflectance can be suppressed. Reduced.

From the viewpoint of effective use of the LED irradiation light, the white film 5 preferably has a reflectance of 70% or more for a visible light region of 400 to 800 nm, and in a more preferable embodiment, a pair of 460 nm (blue) The color ratio is preferably 525 nm (red) and 620 nm (red) with a reflectance of 70% or more.

Further, the thermal conductivity of the white film 5 is preferably smaller than the thermal conductivity of the insulating layer 2.

If the thermal conductivity of the white film 5 is smaller than the thermal conductivity of the insulating layer 2, the heat of the LED package does not pass through the circuit portion and dissipates heat from the white film. Therefore, the temperature of the gas environment near the LED does not easily rise. The life of the LED can be increased.

Further, in order to maintain the mechanical strength, the metal base circuit substrate preferably has a total thickness of 265 μm or more and 500 μm or less.

Further, the metal base circuit board preferably has a bending amount of 3 mm or less on a metal base circuit board having a length of 100 mm.

Further, the amount of warpage used in the present invention means that the non-circuit portion 4 and the circuit portion 3 on the insulating layer 2 are above, and when the surface is placed on a smooth and parallel surface, the upper surface is defined as a concave portion. It is "+: positive" and defines the following as "-: negative". The absolute value of the bending is the maximum height of the smooth and parallel faces of the outer periphery of the metal base circuit substrate.

The outer shape of the metal base circuit substrate of the present invention is preferably a combination of the upper and lower sides, and preferably a square or a rectangle. Further, in the case where it is difficult to design the outer shape to be vertically symmetrical with respect to the design, it is preferable to perform a process such as slitting on the outer periphery of the circuit board.

The metal base circuit substrate of the present invention can have good heat dissipation characteristics without using sub-members and heat dissipation holes, so that the life of the LED can be prolonged and the amount of bending can be suppressed, thereby improving the circuit formation of the printed circuit board. As for the workability of the LED mounting, it is extremely useful as a metal base circuit board for LED backlights.

The embodiments of the present invention have been described above, but these are merely examples of the present invention, and the present invention can adopt various configurations other than the above.

[Examples]

Hereinafter, the examples and comparative examples of the present invention will be described in detail with reference to the drawings and Table 1, but the present invention is not limited thereto.

As shown in Fig. 1, the metal base circuit board of the present invention has a metal foil 1; an insulating layer 2 formed on one surface of the metal foil 1, and a surface not provided with the metal foil 1 formed on the insulating layer 2. The upper circuit portion 3 and the non-circuit portion 4; and the white film 5 formed on the insulating layer 2, the circuit portion 3, and the non-circuit portion 4. Further, the symbol 7 in the figure is an LED package.

[Examples]

The metal base circuit substrate of Example 1 was produced in the following manner.

The insulating layer 2 was formed on a copper foil having a thickness of 35 μm, and the thickness of the insulating layer 2 after hardening was 150 μm.

The insulating layer 2 is a bisphenol A type epoxy resin ("EPICLON-828" manufactured by Dainippon Ink and Chemicals Co., Ltd., and added as a amine hardener, diaminodiphenylmethane (manufactured by Nippon Synthetic Chemical Co., Ltd., " H84B") is a hardening agent, and is composed of pulverized cerium oxide ("A-1", manufactured by Ronson Co., Ltd.) having an average particle diameter of 1.2 μm and crushed coarse cerium having an average particle diameter of 10 μm. ("SQ-10" manufactured by Lin Huacheng Co., Ltd.) was formulated so as to be 35 vol% (the mass ratio of spherical spherules to spherical granules was 6:4) in the insulating layer.

Then, an aluminum foil having a thickness of 200 μm was bonded, and the insulating layer 2 was cured by heating to obtain a metal base substrate having a sodium ion concentration of 50 ppm or less in all the inorganic fillers in the insulating layer 2.

Further, the obtained metal base substrate is covered with a resist to cover a predetermined position, and the copper foil is etched so that the circuit portion and the non-circuit portion have various total areas, and then the resist is removed to form a copper circuit portion. 3 and the non-circuit portion 4 are formed as a metal base circuit substrate.

Further, a white solder resist is applied onto the metal base circuit board as a white film 5 having a high reflectance, and is cured by heat and ultraviolet rays.

At this time, a white coating film is not formed on the LED package mounting portion on the circuit portion 3. As a white solder resist, "SSR-6300S" manufactured by Shanrong Chemical Co., Ltd. is used.

As shown in Table 1, in the first embodiment, the total area of the non-circuit portion 4 and the circuit portion 3 on the insulating layer 2 is 79% with respect to the area of the metal foil 1, and the linear expansion coefficient of the metal material constituting the metal foil 1 is At 23.9 ppm/° C., the linear expansion coefficient of the insulating layer 2 was 91.3 ppm/° C., and the linear expansion coefficient of the circuit portion 3 and the non-circuit portion 4 was 17.5 ppm/° C.

The content of the inorganic filler relative to the total volume of the insulating layer 2 was 35%, and the resin used for the insulating layer was used as an epoxy resin, and an amine hardener was added to the insulating layer.

As shown in Table 1, in Example 1, the amount of bending was a good value of 1.7 mm and 3 mm or less.

As shown in Table 1, Example 2 was produced in the same manner as in Example 1 except that the content of the inorganic filler relative to the total volume of the insulating layer 2 was 56%.

In Example 2, the amount of bending was a good value of 1.1 mm and less than 3 mm.

As shown in Table 1, in the third embodiment, phenolic ("HF-4M" manufactured by Minghe Chemical Co., Ltd.) was used as a curing agent for the insulating layer 2, and an imidazole-based curing catalyst (manufactured by Shikoku Chemicals Co., Ltd., " The same procedure as in Example 1 was carried out except that 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole" was used as a catalyst.

In Example 3, the amount of bending was a good value of 1.8 mm and less than 3 mm.

[Comparative example]

As shown in Table 1, Comparative Example 1 was produced in the same manner as in Example 1 except that the total area of the non-circuit portion 4 and the circuit portion 3 of the insulating layer 2 was 98% with respect to the area of the metal foil 1. to make.

In Comparative Example 1, when the amount of bending was measured, it could not be circuitized.

As shown in Table 1, Comparative Example 2 was produced in the same manner as in the first embodiment except that the total area of the non-circuit portion 4 and the circuit portion 3 of the insulating layer 2 was 30% with respect to the area of the metal foil 1. .

In Comparative Example 2, the amount of warping was 11.4 mm, and a large bending was caused.

As shown in Table 1, in Comparative Example 3, except that the coefficient of linear expansion of the metal foil was 39.7 ppm/°C, and phenol (manufactured by Mingwa Chemical Co., Ltd., "HF-4M") was used as the hardener for the insulating layer 2, They were all produced in the same manner as in Example 1.

In Comparative Example 3, the amount of warping was 4.9 mm and exceeded 3 mm.

As shown in Table 1, Comparative Example 4 was produced in the same manner as in Example 1 except that the insulating layer 2 had a linear expansion coefficient of 127.5 ppm/° C. and the volume % of the inorganic filler was 0.

In Comparative Example 4, the amount of warping was 7.3 mm and exceeded 3 mm.

As shown in Table 1, in Comparative Example 5, the linear expansion coefficient of the circuit portion and the non-circuit portion was 4.3 ppm/° C., and an amine-based hardener and phenolic resin ("HF-4M" manufactured by Mingwa Chemical Co., Ltd.) were used as the insulating layer 2 The hardener used is an imidazole-based hardening catalyst ("2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole" manufactured by Shikoku Kasei Co., Ltd.), and the others are implemented. Example 1 was made in the same manner.

In Comparative Example 5, the amount of warping was 6.7 mm and exceeded 3 mm.

As shown in Table 1, in Comparative Example 6, except that the linear expansion coefficient of the metal foil was 10.5 ppm/° C., the linear expansion coefficient of the circuit portion and the non-circuit portion was 23.9 ppm/° C., so that the linear expansion coefficient of the circuit portion and the non-circuit portion was obtained. The coefficient of expansion of the metal foil is larger than that of the first embodiment, and the same applies to the first embodiment except that an amine hardener and a phenolic resin ("HF-4M" manufactured by Minghe Chemical Co., Ltd.) are used as the curing agent for the insulating layer 2. to make.

In Comparative Example 6, the amount of warping was 9.2 mm and exceeded 3 mm.

As described above, the metal base circuit substrate of the present invention can suppress the amount of warpage of the substrate to less than half as compared with the comparative example. Therefore, the workability at the time of circuit formation of the printed circuit board and the LED mounting can be improved.

1. . . Metal foil

2. . . Insulation

3. . . Circuit part

4. . . Non-circuit part

5. . . White film

6. . . Welding department

7. . . LED package

Fig. 1 is an explanatory view (cross-sectional view) schematically showing an example of a metal base circuit board of the present invention.

1. . . Metal foil

2. . . Insulation

3. . . Circuit part

4. . . Non-circuit part

5. . . White film

6. . . Welding department

7. . . LED package

Claims (4)

A metal base circuit substrate comprising: an insulating layer having a coefficient of linear expansion of 60 ppm/° C. or more and 120 ppm/° C. or less; a metal foil formed of a metal material and disposed on one side of the insulating layer, having a coefficient of linear expansion 10 ppm/° C. or more and 35 ppm/° C. or less; a circuit portion and a non-circuit portion formed on the other surface of the insulating layer, having a linear expansion coefficient of 10 ppm/° C. or more and 35 ppm/° C. or less; and a white film formed on the insulating layer, In the circuit part and the non-circuit part, the total area of the circuit part and the non-circuit part on the insulating layer is 50% or more and 95% or less with respect to the area of the metal foil, and the relationship between the linear expansion coefficients of the respective materials is: the insulating layer The coefficient of linear expansion > the coefficient of linear expansion of the metal foil > the coefficient of linear expansion of the circuit portion and the non-circuit portion. The metal base circuit substrate of claim 1, wherein the insulating layer is formed of an epoxy resin, a hardener, and an inorganic filler, and the inorganic filler contains 40% by volume or more and 70% by volume with respect to the total volume of the insulating layer. the following. The metal base circuit substrate of claim 2, wherein the hardener contains one or both of a hydroxyl group and an amine group. The metal base circuit substrate of claim 1, wherein the white film contains titanium dioxide as a white pigment, the titanium dioxide is rutile type, and the surface is covered with aluminum hydroxide or cerium oxide.